THE OCCURRENCE OF FUSARIUM SPECIES IN CANADA: II. PREVALENCE AND TAXONOMY OF FUSARIUM SPECIES IN CEREAL SEED

Abstract

During the present investigation, a total of 1579 seed samples of wheat, 1042 of barley, and 1152 of oats (100 kernels per sample), were examined microbiologically for the presence of Fusarium. Of these samples, 402 of wheat, 513 of barley, and 636 of oats originated in the seed inspection districts of Eastern Canada, and 1177 of wheat, 529 of barley, and 516 of oats in those of Western Canada. Isolates of Fusarium were obtained from approximately 41.8% of the samples of wheat (1.5% of the kernels), 76.2% of the samples of barley (3.9% of the kernels), and 79.6% of the samples of oats (5.7% of the kernels) that originated in Eastern Canada, whereas only 13,8% of the samples of wheat (0.2% of the kernels), 36.3% of the samples of barley (0.7% of the kernels), and 38.9% of the samples of oats (1.1% of the kernels) from Western Canada yielded Fusarium. In classifying the different wild types of Fusarium that were obtained from cereal seed the system of taxonomy and nomenclature of Wollenweber and Reinking was chiefly followed, but certain sections of the genus were revised extensively, partly in accordance with Snyder and Hansens' concept of species in this genus. Four new combinations are proposed, namely F. compactum (Wr.) n. eomb., F. lateritium Nees emend. Snyder & Hansen forma cajani (Padwick) n. comb., F. lateritium Nees emend. Snyder &. Hansen forma crotalariae (Padwick) n. comb., and F. oxysporum Schlecht. emend. Snyder & Hansen var. redolens (Wr.) n. comb. A total of 16 species and varieties of Fusarium, classified in nine sections of the genus, was isolated from cereal seed during this investigation. These species and varieties are, namely, F. poae (Pk.) Wr., F. sporotrichioides Sherb., F. avenaceum (Fr.) Sacc, F. arthrosporioides Sherb., P. semitectum Berk. & Rav., F. equiseti (Cda.) Sacc, F. acuminatum Ell. & Ev., F. culmorum (W. G. Sm.) Sacc, F. graminearum Schwabe, F. sambucinum Fuckel, F. sambucinum var. coeruleum Wr., F. lateritium Nees emend. Snyder & Hansen, F. moniliforme Sheld. emend. Snyder & Hansen, F. oxysporum var. redolens (Wr.) n. comb., and F. solani (App. & Wr.) Wr. emend. Snyder & Hansen. F. poae, F. avenaceum, and F. acuminatum were most frequently isolated. F. concolor Rg. and F. sambucinum f. 6 Wr,, that were previously recorded from cereal seed in Manitoba, and three additional species, namely, F. dimerum Penz., F. merismoides Cda., and F. nivale (Fr.) Ces., that may be encountered in the future among isolates from cereal seed in Canada, were also included in this study.